SquirrelMail access

I have some problem with SquirrelMail account, the matter is when I am accessing SquirrelMail via Cpanel, it is showing me webmail page with Horde Mail and SquirrelMail, and when I am choosing SquirrelMail it is showing me login page again.
Somebody what is the problem, please help
Many Thanks

I am currently having this problem with an account I added a few days ago. All other domains on the server can access squirrelmail with no problem, all accounts in this new domain get "User unknown or incorrect password"

OK, I figured out what was wrong with mine. For the new domain I created none of the files that should have been created in /etc/vmail were created. I'll have to figure out why that is, but I created all of the files and symbolic links manually and the users from that domain can login to Horde and Squirrelmail now.

I have searched the forums and see lots of folks with this problem. Has anyone figured out how to fix the issue that causes the problem? I'd like to correct the root cause but have not seen any posts on what exactly is not working or how to fix it. Am I waiting for a new release?!?